#include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; const int MAX = 510000; const int MOD = 1000000007; long long fac[MAX], finv[MAX], inv[MAX]; // テーブルを作る前処理 void COMinit() { fac[0] = fac[1] = 1; finv[0] = finv[1] = 1; inv[1] = 1; for (int i = 2; i < MAX; i++) { fac[i] = fac[i - 1] * i % MOD; inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD; finv[i] = finv[i - 1] * inv[i] % MOD; } } // 二項係数計算 long long COM(int n, int k) { if (n < k) return 0; if (n < 0 || k < 0) return 0; return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD; } int main() { int N; cin >> N; long long A[250000]; for (int i = 1; i <= N; i++)cin >> A[i]; long long answer = 0; COMinit(); for (int i = 1; i <= N; i++) { answer = answer + A[i] * COM(N - 1, i - 1); answer=answer%MOD; } cout << answer << endl; }